Method of making sheet-metal gearing.



A. JOHNSTON. METHOD MAKING SHEET METAL GEARING. ATPPLIOATION rum) MAY 27, 1909.

988,106, Patented Mar. 28, 1911.

wimm M 1 WWFW" Warm ALLEN JOHNSTON, OF OTTUMWA, IOWA.

METHOD OF MAKING SHEET-METAL GEARING.

Specification of Letters Patent.

Application filed m 27, 1909. Serial No. 498,732.

To all whom 'it may concern: V

Be it known that I, ALLEN JOHNSTON, of ()tlumwa, Iowa, have invented a new and useful Improvement in Methods of Making Sheet-Metal Gearing, which invention is fully set forth in the following specification.

This invention relates to a method of making sheet-metal gearing, and has for its object to provide a method whereby gearing of this kind may be cheaply and expeditiously manufactured, and of quality.

With this object in view the method consists in taking a strip of sheet-metal, as for example sheet-steel, of any desired thickness and width and then crimping said strip so as to provide it with a series of regularly formed and spaced crimps to form the teeth of the gearing.- This crimping action may be performed in any suitable manner and by any suitable means, preferably, however,

by the action of the improved crimping machine set forth in my U. S. Patent, No. 944,559, dated December 28, 1909. In forming crimps which are to constitute the teeth of the gearing, the metal is bent at the crown of the teeth or crimped sharply upon itself so as to bring two faces of the metal closely adjacent to each other, the crimping action being such as to form the teeth approximately alike and with approximately uniform spaces intervening between the teeth. The strip thus crimped forms an effective gearing for certain classes of work without any additional treatment, but where accuracy and strength of the teeth are required, the gearing is greatly improved by subjecting the same to pressure in a suitable (lie whereby the teeth are forcibly compressed, preferably in the manner of cold forging, so that the teeth are rendered absolutely true and uniform with the adjoining surfaces of the metal constituting each tooth brought into intimate contact throughout the whole or a part of their extent, thereby greatly stifi'ening the tooth and rendering it rigid, and also truing the spaces between the teeth so that the smoothness of finish, regularity of form of the teeth and the spaces, and the rigidity and accuracy of the entire gear, is greatly enhanced over that found in the gearing formed by the original crimping action. l

The crimped strip, either before or after the cold forging in the die to accurately shape the teeth and spaces',may be used for a superior the various forms and varieties of gearing known to the art. Thus, a strip may be used as a rack, or it may be bent into annular form and the ends of the strip preferably joined together by welding, soldering,

Patented Mar. 28, 1911.

or other suitable means, to form either an i external or internal gear-wheel. The accurate shaping, whether said operation is performed by cold forging or other suitable means, 'maybe performed before or after the strip is bent into annular form with its ends united, as indicated above. Preferably,-

however, this operation is performed (when the gearing is to assume the form of a gearwheel) after the crimped strip has been bent into annular form and the en'ds thereof secured together. i

It will, of course, be understood that the distance from center to center of the crowns of adjoining crimps in the crimped strip before it is bent into annular form to make a gear-wheel differs from the distance from the center of the crown of one tooth to the center of the crown of the adjoining tooth in the wheel constructed from such crimped strip, and, therefore, when crimping a strip to construct a gear-wheel of given pitch and with a given number of teeth, it is essential that the crimps of the strip should be formed at such a distance apart that when bentinto annular form to construct a earwheel the crimps forming the teeth of the gear-wheel will have the desired pitch. Thus, if it be desired to construct an external toothed gear-wheel of 14 pitch wlth 115 teeth the distance from center to center of the crowns of the crimped strip should be .210 of-an inch. If the wheel is to be oneof 120 teeth and 14 pitch, the distance from center to center of the crowns in the strip should be .215 of an inch, and if a wheel is to be constructed of 125 teeth and 14 pitch, the crowns in the strip should be .220 of an inch from center to center. It will be observed that in each of these instances this distance from center to center of the crowns of the crimps is less than would be the distance from center to center of the crowns of the teeth of a wheel of the kind indicated. These examples will illustrate the principle indicated above that thedistance from center tocenter of the crowns of the crimped strip should differ slightly from the distance from center to center of the crowns of the teeth in the construction of,which the crimped strip is designed to enter. The

proper distances from center to center of the crimps may be readily computed for any desired pitch and for a wheel of any desired number of teeth.

gear-wheel, the annular crimped strip of metal may be mounted directly on a shaft, or, if preferred, may be mounted on a suitable body portion composed either of sheetmetal, as set forth'in my U. S. Patent No. 951,503, dated March 8, 1910, or on any other suitable body. a

The method of constituting the invention may be practiced by the use of a variety of forms of tools and apparatus, the particular tools for crimping, shaping, forging and uniting the ends of the strips, etc., forming no part of the invention.

For the purpose of illustrating the invention, reference is had to the accompanying drawings, which drawings, however, are em: plrziyed merely for purposes of illustration an not for the purpose of defining the limits of the invention, reference being had to the claims for this purpose.

In said drawings-Figure 1 represents a strip of sheet-metal, as of sheet-steel or sheet-brass, of any suitable or desired width and thickness; Fig. 2 is a side elevation of said strip after the same has been'crimped and before the teeth have been shaped by cold forgin or otherwise; Fig. 3 shows the condition 0 said crimped strip after it has been shaped by cold for ing or other treatment under pressure; ig. 4 shows the crimped strip of Fig. 2 bentinto annular form with its ends united to form an ex ternal gear-wheel; Fig. 5 shows the earwheel of Fig. 4 after it has been shape under pressure, preferably by cold forging; Fig. 6 shows a section of an internal gearwheel before the same is shaped; and Fig. 7 shows a section of an internal gear-wheel after truing or shaping.

Referrin to the drawings, 6 (Fi 1) indicates a p ain stri of sheet-meta of any desired length, widiih and thickness. This strip of sheet-metal is suitably crimped by the use of a proper crimping machine, or other ap aratus, into the shape shown in Fig. 2, t e crimps 7 being only approximately uniform, as are also the spaces 8 between the crimps, and with the adjoining surfaces of that plortion of the metal constituting each toot as indicated at 9, very nearly or quite contacting. By the use of a suitable crimping apparatus it is possible to bring the surfaces 9 into actual contact and to form the teeth 7 and the spaces 8 of a very considerable uniformity, so much so, in fact, that the crimped strip as crimped, and without any additional operation of shaping the' teeth and spaces b cold forging or otherwise, may be employe as a gearing either in the form of a rack or gear-wheel, or any eaaioe other suitable or desired form of gearing. In general practice, however, and for the better forms of gearing, it is found desirable to accurately shape the teeth 7 and the When the gearing assumes the form of a spaces 8 by subjecting the same to pressure, and this is accomplished by subjecting the same to the action of a die under pressure, preferably when cold, so that the crimped stri is really cold forged, the action of the die being to bring the adjacent surfaces at 9 into intimate contact with each other throughout the whole or a part of their extent and to shape each of the teeth 7 so that they are alike, and to likewise form the spaces 8 so that they are. alike, as clearly shown in Fig. 3, thus providing a gearing which Willbe perfectly true and accurate in operation. In addition to this the com 'acting of the metal forming the teeth 0 the gear renders said teeth perfectly rigid, and eliminates'any elasticity that would reside in the crimped teeth where the surfaces 9 were not in intimate contact.

The crimped strip, as shown in Fig. 2, may be formed into a gear-wheel by bending the same into annular form and uniting the ends of the strip in any suitable manner, as by soldering or by welding, as shown at 10 in Fig. 4. This forms a gear-wheel with approximately uniform teeth 7 and spaces 8 which may be used in certain rough forms of machinery, but to form a true and accurate ear-wheel the annular gear-wheel of Fig. 4 1S subjected to a truing operation by the use of any suitable apparatus. Preferably, this is performed by cold for ing the wheel of Fig. 4 by the use of suitable dies, though the truing action is not necessarily limited to cold orging by dies, since any desired or convenient apparatus for accomplishing this end may be employed.

While it is indicated above that the truin operation on, the gear-wheel is performe after the same has been bent into annular form and the ends united together, it is not to be understood that the invention is limited to performing the truing action after the bending of the crimped strip, since, if desired, the teeth 7 and the spaces 8 may be trued, as by cold forging, or otherwise, while the same is in the form shown in Fig. 2, thus producing the trued crimped strip of the form shown in Fig. 3, and this trued strip --then bent into annular form to produce the perfected and accurate gear-wheel of Figs. 5 or 7. Preferably, however, the crimped strip of Fig. 2 is first bent into the annular form shown in Fig. 4, the ends of the strip then united as by welding, cold so1derii1g,or otherwise, and the same then trued as by cold forging, or otherwise, into the completed gear-wheel of Figs. 5 or 7.

The gearheel of Fig. 4, or the trued wheel of Fig. 5, may be mounted on any suitable body, either solid, or formedwith spokes and a suitable rim, as desired, or it may be keyed directly to a suitable shaft, or otherwise secured thereon.

It will be apparent that the invention is equallyrapplicable to plain or beveled gear- 111 s Obvious changes in the specific details herein described which will not involve departure from the inventive idea of the method set forth will suggest themselves to the skilled mechanic, and such obvious changes are designed to be within the scope of the atentees claims. 7

Having thus described the invention, what I claim is 1. The rocess of making sheet-metal gearing, w ich consists in crimping a strip of sheet-metal into gear-teeth with the a jacent surfaces of the sheet-metal on the in ner side of each tooth approximately contacting, and then bringing said adjacent surfaces into intimate contact under pressure.

2. The process of making sheet-metal gearing, which consists in crimping a stripof sheet-metal into gear-teeth with the adacent surfaces of-the sheet-metal on the inner side of. each tooth approximately conta'ctin and [then subjecting said teeth to a col forging operation to bring said adacent surfaces into contact and to stiffen and accurately space the-same.

'3. The process of making sheet-metal gearing, which consists in crimping a strip of sheet-metal into gear-teeth with the adjacent surfaces of 'the sheet-metal on the inner side of each tooth approximately contacting, and then bringing said adjacent surfaces into intimate contact by cold forging.

4. The process of making sheet-metal gearing, which consists in crimping a strip of sheet-metal to form rough gear-teeth approximately alike with the adjacent suraces of the sheet-metal forming each tooth,

approximately contactin then bending said crimped strip into annu ar shape to form a gear-wheel, and bringing said surfaces. into intimate contact'by cold forging.

5. The process of making sheet-metal gearing, which consists in -crimping a strip of sheet-metal .to form rough gear-teeth approximately alike, bending the crimped strip into annular shape to for m a gear-wheel, unitin the ends of said strip, and then accurate y shaping said teeth and the intervening spaces under pressure.

6. The rocess of making sheet-metal gearing, w ich consists in crimping a strip of sheet-metal tofform rough gear-teeth approximately alike, bending the crimped strip into annular shape to form a gear-wheel, uniting the ends of said strip, and then accurately shaping said teeth and the intervenin spaces by cold forging. v

7. he process of making sheet-metal gearing, which consists in crimping a strip of sheet-metal to form rough gear-teeth apto the desired number of teethin a gear wheel to be made, bending said severed por-- tionQinto approximately annular form, uniting the adjacent ends and then-truing the teeth simultaneously by bringing the adjacent surfacesof the sheet-metal forming each tooth into intimate contact under pressure to -reduce them to exact uniform size and pitch.

9. The process of makin gearing, which consists in crimping a'strip of sheet-metal into gear-teeth with the adjacent surfaces of the sheet-metal on the inner side of each tooth approximately contacting and then bending said crimped strip below the pitch line into an annular shape to form a gear-wheel, at the same time increasing the distance from center to center of the teeth on the pitch line.

10. The process of making sheetmetal,

gearing, which cpnsists in crimping a strip of sheet-metal into gear-teeth with the a jacent surfaces of the sheet-metal on the inner side of each tooth approximately contacting and then bending said crimped strip below the pitch line into an annular shape to form a gear-wheel, at the same time changing'the distance-from center-to cen-' ter of the teeth on the'pitch line.

In testimony whereof I have signed this ing witnesses.

Witnesses R. W. FENCE, F; A. Wn errr.

sheet metal ALLEN JOHNSTON.

specification inthe presence of two subscrib- 

